Cable and power
Phantom Power Requirements Chart
Quick answer
Phantom power is 48 volts fed through two 6.8 kilohm resistors, supplying up to 10 milliamps per channel under IEC 61938. Condenser microphones and active direct boxes need it, dynamic microphones ignore it, and a ribbon microphone on a faulty cable can be destroyed by it.
Phantom power gets its name from being invisible: the same two conductors that carry the audio also carry the supply, at equal voltage on both legs, so a microphone that does not want it never sees a difference between them. That elegance is why almost every church console has one button marked 48V, and why almost every church has at some point switched it on for everything and hoped.
Mostly that is harmless. Dynamic microphones genuinely ignore it. But there are two real exceptions, one of which destroys an expensive microphone, and there is a quieter problem that affects every church with a lot of condensers: a console’s phantom supply is shared, and it can run out. This chart covers what needs it, how much each device draws, and where the limits are. Channel counts are in the input list template.
On this page
What are the phantom power standards?
Three standards exist under IEC 61938, and only one of them matters in practice. P48 is what every modern console supplies and what every modern condenser expects. The other two survive in older equipment and in some battery powered mixers.
P48 supplies 48 volts through two 6.8 kilohm resistors with a maximum of 10 milliamps per channel, which is the standard every current console and condenser microphone is built around.
| Standard | Voltage | Series resistor per leg | Max current | Where you meet it |
|---|---|---|---|---|
| P48 | 48 V, plus or minus 4 V | 6.8 kilohm | 10 mA | Every modern console, interface and stage box. The default. |
| P24 | 24 V, plus or minus 4 V | 1.2 kilohm | 10 mA | Older broadcast equipment and some portable mixers. |
| P12 | 12 V, plus or minus 1 V | 680 ohm | 15 mA | Rare. Some battery powered and legacy field equipment. |
| T-power, A-B | 12 V across the pair | n/a | 15 mA | Not phantom at all. Film production legacy. Will damage phantom microphones. |
| Plug-in power | 3 to 5 V | n/a | Under 1 mA | Consumer 3.5 mm inputs on cameras and recorders. Unrelated to P48. |
| Bias from a bodypack | 2 to 10 V | n/a | Under 2 mA | Wireless transmitters power their own capsule. No console phantom involved. |
The two 6.8 kilohm resistors are why phantom is safe for dynamic microphones: they limit the available current so heavily that a short across the pair, which is what a dynamic microphone’s coil looks like, simply sits there. A microphone specified for a lower standard may work at reduced headroom on P48 or may not work at all, but T-power is genuinely incompatible and will damage a phantom microphone.
What needs phantom power, and how much does it draw?
The working list. The current column matters once a church has more than a dozen condensers, because a console supplies a shared budget rather than 10 mA per channel regardless.
A condenser microphone draws 2 to 7 milliamps and an in-line preamp can draw 9 milliamps, close to the 10 milliamp per channel maximum the standard allows.
Current figures are typical published draws for these device classes; confirm against the specification sheet for your exact model. The 10 milliamp figure in the standard is the maximum a compliant supply must provide per channel, not what a device draws. Most condensers sit between 2 and 5 milliamps.
Can my console supply phantom to every channel?
This is the question nobody asks until a service where four hanging choir microphones go quiet and nobody can explain it. A console has one phantom supply feeding all channels, sized for a realistic load rather than for every channel drawing the maximum at once.
Sixteen condenser microphones drawing 5 milliamps each demand 80 milliamps from a shared supply, and the same sixteen channels all drawing the 10 milliamp maximum would demand 160 milliamps.
| Channels on phantom | Typical draw at 5 mA | Worst case at 10 mA | Realistic church load |
|---|---|---|---|
| 4 | 20 mA | 40 mA | Two goosenecks and two hanging choir mics. No console will struggle. |
| 8 | 40 mA | 80 mA | Adds drum overheads and a piano pair. Still comfortable. |
| 12 | 60 mA | 120 mA | A full choir array plus active DIs. Watch small mixers here. |
| 16 | 80 mA | 160 mA | A typical mid-size church with condensers everywhere. |
| 24 | 120 mA | 240 mA | Large platform. Check the console specification explicitly. |
| 32 | 160 mA | 320 mA | Multi-campus scale. Assume a distributed supply is needed. |
| 48 | 240 mA | 480 mA | Beyond a single console supply on most designs. |
Compact and inexpensive mixers are the ones that sag, and the symptom is not silence but reduced headroom: condensers distort early on loud sources while still passing quiet ones normally. If a church is running more than about a dozen condensers, check the console’s published total phantom current before adding more, and move active direct boxes onto a stage box with its own supply where possible.
What phantom power damages, and what it does not
Dynamic microphones are genuinely safe. A dynamic capsule is a coil, which looks like a short across pins 2 and 3. Because both legs sit at the same voltage, no current flows through the coil, and the 6.8 kilohm resistors limit what is available anyway. Leaving phantom on across a whole console with a platform full of SM58s does nothing at all. The widespread belief that it harms them is folklore.
Passive ribbon microphones are the real exception. A ribbon is a thin strip of foil that moves in a magnetic field, and it is mechanically fragile in a way nothing else on a platform is. With an intact, correctly wired cable, phantom applied to a ribbon is survivable on most modern designs. With a faulty cable, or a plug being inserted while phantom is live, the two legs are momentarily at different voltages and current flows straight through the ribbon. That stretches or tears it, and the repair costs more than most church microphones. Active ribbons, confusingly, require phantom, so read the badge rather than reasoning from the type.
Patching with phantom live is the avoidable risk. Inserting or removing an XLR while 48 volts is applied produces a loud thump through the system and a momentary imbalance at the connector. Turn phantom off for the channel, patch, then turn it back on. On a digital console this is two taps and it costs nothing.
Line outputs should never be fed phantom deliberately. A modern balanced output tolerates it, but an older transformerless output or a piece of consumer equipment may not. The rule that keeps a church out of trouble is simple: phantom on for condensers and active direct boxes, off for everything else, set per channel rather than globally.
Where this chart does not apply
Wireless systems do not use console phantom at all. A headset or lavalier on a bodypack takes a low voltage bias from the transmitter, not 48 volts from the desk. Switching phantom on for a wireless receiver’s output achieves nothing. This catches churches out when a wired headset such as the Shure SM35 Performance Headset Condenser Microphone - TQG is swapped onto a wireless transmitter and stops working, because the termination and the powering are both different.
Plug-in power is not phantom. The 3 to 5 volts on a camera or recorder’s 3.5 mm input powers consumer electret capsules and is unrelated to P48. A professional condenser will not run on it, and a microphone designed for it will not survive P48.
Global phantom switches are a design compromise. Some inexpensive mixers switch phantom for the whole console or for blocks of eight channels. That forces phantom onto channels that do not want it, which is usually harmless but removes the ability to protect a ribbon or to patch safely. If a church owns ribbons, per-channel switching is a requirement rather than a preference.
It does not cover voltage sag over long cable runs. Very long microphone runs, particularly to hanging choir microphones in a high ceiling, drop a little voltage along the way. Modern condensers with an 11 to 52 volt tolerance absorb this easily, but a microphone specified for 48 volts exactly may lose headroom at the end of a 300 foot run.
It says nothing about gain. Phantom powers the microphone; it does not amplify it. A condenser still needs the preamp set correctly, which is gain structure, and a low output dynamic still needs the gain a console can deliver rather than an in-line preamp bolted on afterwards.
Sources
- IEC 61938 phantom powering standard, defining P48, P24 and P12 supply voltages, source resistances and maximum current
- Published phantom current draw figures from manufacturer specification sheets for the microphone and direct box classes listed
- AES14 balanced interconnection convention, which is what makes phantom powering transparent to dynamic microphones
Frequently asked questions
What needs phantom power?
Condenser microphones and active direct boxes. That covers gooseneck pulpit microphones, hanging choir microphones, boundary microphones, clip-on instrument condensers, wired headsets and lavaliers, and active DIs such as the Radial Pro48. Dynamic microphones, passive direct boxes and wireless receiver outputs need nothing. Active ribbon microphones also require it, which is the one case where the type name misleads.
Does phantom power damage dynamic microphones?
No. This is folklore. A dynamic capsule is a coil that looks like a short across pins 2 and 3, and because both legs sit at the same voltage no current flows through it. The two 6.8 kilohm series resistors limit the available current heavily in any case. Leaving phantom switched on across a platform full of SM58s does nothing at all.
What can phantom power actually destroy?
A passive ribbon microphone, and only under specific conditions. With an intact cable most modern ribbons survive it, but a faulty cable, or plugging in while phantom is live, puts the two legs at different voltages momentarily and sends current straight through the foil ribbon. That stretches or tears it, and the repair costs more than most church microphones.
How much current does phantom power supply?
Up to 10 milliamps per channel under the P48 standard, delivered at 48 volts through two 6.8 kilohm resistors. Most condenser microphones actually draw 2 to 5 milliamps. Active direct boxes draw 4 to 10 milliamps and in-line preamps sit at the top of the range around 9 milliamps, which is worth knowing when planning a channel count.
Can my mixer run phantom on every channel at once?
Larger consoles can, but compact and inexpensive mixers often cannot supply the full budget to every channel simultaneously. The symptom is not silence but lost headroom, with condensers distorting early on loud sources while quiet material sounds normal. Past about a dozen condensers, check the console’s published total phantom current before adding more.
Should I turn phantom power off before unplugging a microphone?
Yes, and mute the channel too. Inserting or removing an XLR with 48 volts live produces a loud thump through a system at service level and creates a momentary imbalance at the connector, which is the exact condition that damages ribbons. On a digital console it is two taps. Make it part of the changeover routine between services.
Researched, not professional advice. This page is compiled from published manufacturer specifications, operator manuals, FCC rules, published standards and owner-review consensus, not hands-on testing. Sound system design, rigging loudspeakers overhead, and any electrical work are jobs for a qualified professional: have flown loudspeakers and their attachment points signed off by a structural engineer or a certified rigger, and have all wiring done by a licensed electrician to your local code. Wireless microphone rules change, so confirm the current FCC position before buying. As an Amazon Associate we earn from qualifying purchases.